First Dorsal Interosseous Muscle of Foot

Origin

The first dorsal interosseous muscle of foot consists of two heads:

- the medial head, which originates from the lateral aspect of the body of first metatarsal bone;

- the lateral head, which originates from the medial aspect of the body of second metatarsal bone.

Insertion

The fibers of the first dorsal interosseous muscle of foot travel anteriorly to the second toe and insert, via a short tendon, onto the:

- medial aspect of the base of the proximal phalanx of second toe;

- extensor expansion of second toe.

Key Features & Anatomical Relations

The first dorsal interosseous muscle of foot is located in the fourth layer of muscles that are found in the plantar part of the foot. It is a short, bipennate skeletal muscle.

It is located:

- superior to the adductor hallucis muscle, and the first lumbrical muscle of foot;

- medial to the second metatarsal bone;

- lateral to the first metatarsal bone.

The dorsalis pedis artery travels in between the two heads of the first dorsal interosseous muscle of foot.

Actions

The first dorsal interosseous muscle of foot is involved in multiple actions:

- medially abducts the proximal phalanx of second toe (i.e., medially draws it away from the longitudinal axial line of the second toe) at the second metatarsophalangeal joint;

- simultaneously flexes the second metatarsophalangeal joint and extends the interphalangeal joints of the second toe, which occurs when the first lumbrical and second dorsal interosseous muscles of foot contract simultaneously with it (Standring, 2016).

The first and second dorsal interossei muscles insert on opposite sides of the proximal phalanx of second toe. Their simultaneous contraction cancel out each other’s movements, resulting in the second toe remaining in the anatomical position.

List of Clinical Correlates

- Clawing of the toes

- Charcot-Marie-Tooth disease

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.

Actions

The first dorsal interosseous muscle of foot is involved in multiple actions:

- medially abducts the proximal phalanx of second toe (i.e., medially draws it away from the longitudinal axial line of the second toe) at the second metatarsophalangeal joint;

- simultaneously flexes the second metatarsophalangeal joint and extends the interphalangeal joints of the second toe, which occurs when the first lumbrical and second dorsal interosseous muscles of foot contract simultaneously with it (Standring, 2016).

The first and second dorsal interossei muscles insert on opposite sides of the proximal phalanx of second toe. Their simultaneous contraction cancel out each other’s movements, resulting in the second toe remaining in the anatomical position.